Many types of fluid conduits can benefit from a re-closeable outlet end, especially if such re-closure is automatic. For example, for many bag-in-box types of storage and dispensing systems, a drainage tube or spigot typically extends out of the bag to deliver the fluid content of the bag. Whether the drainage tube or spigot delivers directly to a separate receptacle, e.g., a drinking cup, or is further connected to a second conduit for further processing, it would be desirable to have a mechanism to close the outlet end when delivery is not needed, e.g., when switching bags out of the box. For economical reasons, it is often advantageous that such a mechanism be provided in the form of a reusable device: a connector or fitting that can be attached and detached from various conduits' outlet ends.